High speed circuit breaker



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United States Patent M HIGH SPEED CIRCUIT BREAKER Challis I. Clausing, Westmont, N.J., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application May 22, 1957, Serial No. 660,970

20 Claims. (Cl. 200-93) My invention relates to a novel high speed circuit breaker and more particularly relates to a high speed circuit breaker having a novel magnetic latch unit and a novel blowout coil construction.

Presently used high speed circuit breakers of the type set forth in United States Patent No. 2,412,247, issued December 10, 1946, entitled Circuit Breaker Holding Magnet and Armature, to D. I. Bohn, assigned to the assignee of the instant invention, employ a magnetic latch structure that has a stationary magnet and a movable armature which is operatively connected to the movable contact. In order to impart trip-free characteristics to the circuit breaker, a relatively complex operating mechanism operatively connects the movable contact to an operating source of power. Furthermore, the magnetic latch structure in itself is complex and expensive to manufacture.

The principle of my invention is to provide a relatively simple and inexpensive magnetic latch which is constructed to form a trip-free connection between an operating mechanism and the movable contact structure to thereby eliminate the heretofore used trip-free linkages. As well as providing a less complex system, I have further found that my novel invention substantially improves the trip characteristics of the circuit breaker.

In a preferred embodiment of my novel invention, I provide a novel magnetic latch for latching the circuit breaker contacts in their engaged position which is comprised of two pivotally mounted sections, one of which is the armature section which is operatively connected to a movable contact assembly and the other being the magnet which latches the armature in its engaged position. closing mechanism which could be of any desired type such as the manually operable type, solenoid plunger type, or motor operated type. The latter motor operated type is best seen in copending application Serial No. 660,982, filed May 22, 1957, entitled Motor Closing Mechanism for Circuit Breakers, to Challiss I. Clausing and Frank J. Pokorny, and assigned to the assignee of the instant invention.

The armature member of the magnetic latch is magnetically scalable to its cooperating magnet by means of Another flux source which produced a flux having a magnitude proportional to the current flowing through the circuit breaker contacts is positioned to increase the net flux linkages between the magnet and the armature during normal conditions.

In the event of fault conditions, such as current reversal in a D.-C. breaker, the flux proportional to the contact current is reversed, and opposes the flux of the polarizing coil. Thus the net flux sealing the armature to the magnet is decreased to a point which allows the armature to means, thereby allowing the contact mechanism to be The magnet is then operatively connected to a' i operated to a disengaged position independently'of the 2,891,123 Patented June 16, 1959 ICC circuit breaker operating mechanism operatively connected to the magnet.

In using this novel structure, it has been found that operating speeds are increased over the operating speeds attained with the normally used magnetic latch set forth in the above-noted Patent No. 2,412,247 wherein the magnet is stationarily mounted and the armature is the only movable element of the magnetic latch structure.

Furthermore, it is seen that my novel magnetic latch achieves trip-free characteristics independently of relatively complex trip-free mechanism associated with the closing mechanism as has been the practice heretofore. That is to say, when the circuit breaker contacts are to be moved to their engaged position, the armature and magnet are sealed so as to form a single unit. The circuit breaker operating mechanism operatively connected to the magnet can then drive the circuit breaker cooperating contacts through this rigid magnetic connection.

If, however, the circuit breaker contacts engage on a fault, the armature will be released from its cooperating magnet and the contact structure will move independently of the operating mechanism. A time delay resetting means is then provided which will allow the operating mechanism and magnet to be reset slowly so that the magnet will slowly reengage the armature in the disengaged position whereby the polarizing flux will reseal the armature and the magnet and a new closing sequence is repeated.

Although the movement of the magnet tothe disengaged position is slow, the release of the armature and disengagement of the contacts will occur at the highest possible speed so as to efiectively interrupt the fault.

It is to be noted that the reengagement of magnet and armature preferably takes place relatively slowly so that their cooperating faces, which may be polished, will not be damaged.

In the past, the flux proportional to the current flowing through the circuit breaker contacts has been taken from a so-called bucking bar which is a current conductor connected in series with cooperating contacts and positioned internally of the magnet. This bucking bar type construction has many disadvantages, since it requires an increase in the copper path within the circuit breaker and it requires that the magnet of the magnetic latch be stationarily mounted. Furthermore, it forces the latching mechanism structure to be relatively complex and expensive.

In my novel magnetic latch structure, I have avoided the use of the bucking bar by utilizing a novel magnetic shunt which is positioned to have the normal current conductors within the circuit breakers to pass through its center to thereby create a flux within the magnetic shunt which is functionally related to the circuit breaker current. The magnetic shunt is stationarily mounted and has an air gap which receives the magnet assembly of the magnetic latch when the magnet is in its engaged position with respect to the contact assembly. Thus, the flux through the magnetic shunt is applied to the magnet so that when current conditions within the circuit breaker are normal, the flux of the polarizing coil will be aided in sealing the armature to the magnet.

When, however, there is a fault on the line as indicated by the current through the circuit breaker contacts, and therefore, through the magnetic shunt, the flux of the magnetic shunt is reversed so as to decrease the net flux between the sealing magnet and its armature to thereby allow the armature and the cooperating contacts operatively connected thereto to be quickly driven to a disengaged position.

Accordingly, a primary object of my invention is to provide a novel magnetic latch structure for high speed circuit breakers, I

.closing sequence of operation.

Another object of my invention is to provide a novel magnetic latch structure which is simple in construction and relatively inexpensive to manufacture.

Still another object of my invention is to provide a magnetic latch for high speed circuit breakers which includes a first portion or armature member operatively connected to a contact mechanism and a second portion or magnet member operatively connected to an operating mechanism wherein both the armature member and the magnet member are rotatably mounted and are sealable to one another.

Yet another object of my invention is to provide a magnetic latch structure for high speed circuit breakers which operates as a disengageable clutch for connecting an. operating mechanism to a contact mechanism, this clutch being disengaged responsive to fault conditions on the line.

A further object of my invention is to provide a novel magnetic latch structure which has an extended range of tripping conditions and imparts trip-free characteristics to the breaker.

Another object of my invention is to provide a magnetic shunt having a flux circulating therein proportional to the circuit breaker contact current and having a relatively movable magnet assembly positioned within an air gap wherein reversal of the flux of the magnetic shunt decreases the flux linkages between the magnet and a cooperating armature.

A still. further object of my invention is to replace a bucking bar of a magnetic latch unit by a magnetic shunt.

In cooperation with my novel magnetic latch structure,

'I have provided a novel anti-bounce structure for preventing rebounding of the movable contact structure after it is moved to a disengaged position. This has been a severe problem in the past and has required extensive shock absorbing mechanisms for absorbing the kinetic energy of the movable contact mechanism when it reaches its extreme disengaged position. Since the movable magnet portion of my novel magnetic latch structure moves far more slowly than does the armature member during tripping conditions, I have found that I can position an anti-rebound mechanism on this magnet structure. A cooperating anti-rebound mechanism associated with the movable contact will then be engaged by" the mechanism mounted on the magnet, when the contact structure has reached its extreme disengaged position to prevent contact rebound at the end of the opening stroke. The anti-rebound mechanism is subsequently automatically disengaged when the magnet rotates to its reset position.

This anti-rebound mechanism could include a first open latch member directly connected to the magnet, and a cooperating pin structure operatively connected to the movable contact mechanism. When the movable contact structure is moved to its extreme disengaged position, the open latch mechanism operatively connected to the magnet of the latch structure will be in position to receive the cooperating pin structure of the movable contact mechanism so as to prevent a rebound of the contact structure. After a relatively long time, the magnet portion of the magnetic latch structure is rotated by its reset means to a reset position at which point the armature member may be rescaled to the magnet for a new During this rotation of the magnet, however, the open latch structure attached thereto may disengage the cooperating latch structure attached to the movable contact mechanism whereby the anti-rebound mechanism will be disengaged.

Accordingly, another important object of my invention is to provide a novel magnetic latch structure which is easily adapted to take part in anti-rebound operation.

Another object of my invention is to utilize a magnetic latch having a magnet portion which is slowly reset after circuit breaker operation for mounting anti-rebound mechanism which is positioned to cooperate with the movable contact structure when the movable contact reaches the end of its opening stroke.

Another object of my invention is to provide a novel anti-rebound device which is simple in manufacture and is non-critical in operation.

A further feature of my novel high speed circuit breaker lies in the construction of the blow-out coil which will expose a maximum surface of the blow-out coil area for better cooling.

In the past, the blow-out coil has been a single winding with each turn adjacent to the next turn. Therefore, the inner turns of the blow out coil are not exposed to a cooling medium such as air and the blow-out current or the cross-sectional area of the blow-out coil conductors is limited by this limitation on heat dissipation. I have found that by constructing a blow-out coil of a plurality of parallel connected turns and by providing a first portion of the blow-out winding on a first side of the cooperating contact area, and a second portion of the blowout coil on the opposite side of the cooperating contact area, that I can achieve a maximum cooling surface for the blow-out coil windings. Therefore, I can decrease the cross-sectional area of the blow-out coil conductors since a great amount of heat can now be dissipated for a given steady state current.

Accordingly, a still further object of my invention is to provide a novel blow-out coil construction.

Another object of my invention is to provide a novel blow-out coil construction which cmprises a plurality of parallel connected coils spaced on adjacent sides of the cooperating contact area to thereby increase the available cooling surface of the blow-out coil.

These and other objects of my invention will become apparent from the following description when taken in connection with the drawings, in which:

Figure 1 shows an exploded perspective view of a high speed. circuit breaker utilizing my novel magnetic latch structure and polarizing coil structure.

Figure 1a shows the structure of Figure l in conjunction with a solenoid. type operating mechanism in a partially plan and partially sectional side view.

Figure 2 is a more detailed side view of the lower terminal assembly of Figures 1 and 1a.

Figure 3 is a top view of Figure 2.

Figure 4 is a cross-sectional view of the polarizing magnet structure of my novel magnetic latch.

Figure 5 is a more detailed side view of the upper terminal structure of Figures 1 and la.

Figure 6 is a top view of Figure 5.

Figure 7 is a side view of Figure 5.

Figure 8 is a more detailed side view of the solenoid actuated operating mechanism of Figures 1 and 1a.

Figure 8a is a side cross-sectional view of the sol'enoid mechanism of Figure 8.

Figure 9 is a top view of Figure 8.

Figure 10 schematically illustrates my novel magnetic latch with the cooperating contacts in their engaged position.

Figure 10a shows a top view of the magnetic shunt of Figure 10.

Figure 11 is similar to Figure 10 and illustrates my novel magnetic latch being unlatched responsive to a fault condition.

Figure 12 is similar to Figure 11 and shows the polarizing magnet being reset after the cooperating contacts have been disengaged.

Referring first to Figures 1 and 1a, it is seen that the lower terminals 20 and 22 (Figure 3) are fastenedv to support posts 24 and 26 respectively by the bracket means 2830 and a similar bracket means including bracket 32 of Figure 3 and a bracket not shown, respec tively. These bracket assemblies, as may best be seen, in

Figure 3 for the case of bracket 28, are fastened to their respective lower terminals such as terminal 20 by the nut and bolt means 31 and 34.

As best seen in Figures 1a, 8 and 9, the support posts 24 and 26 are comprised of structural members encased in insulating sheaths 36 and 38 respectively (Figure 1), with the support posts 24 and 26 being rigidly connected to lower angle supports 40 and 42 respectively by bolt means such as the bolt means 44 shown for the lower angle support 40 and its cooperating support post 24.

The upper terminals 46 and 48 as best seen in Figures 1, la and 6 are similarly supported from support posts 24 and 26 having the insulating sheaths 36 and 38 thereon by the bracket means 50--52 corresponding to terminal member 46 and a similar pair of brackets such as brackets 54 of Figure 6 and a second bracket not shown for the upper terminal 48. Clearly the brackets associated with terminal members 46 and 48 are constructed in a manner identical with that set forth for bracket 28 of Figure 3.

A first and a second saddle-shaped support member 56 and 58 best seen in Figures 1, 1a and 2 are then rigidly connected to lower terminals 20 and 22 by the bolt means such as bolts 57, 60 and 62 shown for the case of lower terminal 20 and saddle support member 56 of Figure 1.

As seen in Figure 3, a similar bolt arrangement including bolts 64, 66 and 70 serve to rigidly connect saddle member 58 to lower terminal 22. The bolts 57, 60, 64 and 66 further serve to rigidly connect a conductive bridge member 68 (Figures 1, 1a and 2) which electrically ties the lower terminals 20 and 22 together and further serves as a terminal for the movable contact structure 70, to be described more fully hereinafter.

The front ends of saddle support members 56 and 58 are supported from support posts 55 and 57 respectively (Figures 1, 1a and 9), which are carried by lower angle supports 40 and 42 respectively.

Accordingly, it is seen that the upper and lower terminals 4648 and 20-22 respectively, and saddle support members 56 and 58 are supported from lower angle supports 4042 by support posts 24, 26, 55 and 57.

The saddle support members 56 and 58 serve as a means to mount my novel magnetic latch structure 72 seen in Figure l, as an exploded view, and seen in the assembled view in Figure 1 in dotted lines at location 74.

My novel latch structure as seen in Figures 1, 1a, 2 and 4, comprises a pair of side plates 76 and 78 positioned adjacent either side of the magnetic core member 80 (Figure 4) and fastened thereto by the fastening nut and bolt arrangement, 82. A polarizing coil 84 energized from leads 87 and 88 (Figures 1a and 2) then encompasses the magnetic core member 80 so as to drive a magnetic flux therethrough responsive to energization of the coil 84. The magnetic flux path of the magnet is completed by a front plate 86 which is fastened to the side plates 76 and 78 in any desired manner, as by bolts 75, 77, 79 and 81.

If desired, this front plate 86 of Figures 1 and 4 may be constructed to have non-metallic segments such as segments 88 and 90 interposed between adjacent magnetic segments as seen in Figure 1.

The armature member 92 is then seen in Figures 1, la and 2 as being positioned to move into and out of engage- 'ment with the surface of front plate 86 which is away from the side plates 76 and 78. The armature member 92 which, as will be presently seen, is operatively connected to the movable contact of the circuit breaker may be constructed to have magnetically insulating sections similar to sections 88 and 90 of the front plate 86 wherein the non-magnetic portions of the armature member are in alignment with the magnetic portions of the face plate 86.

Accordingly, the magnetic flux path which will interthe armature and the face plate will be forced to enter the armature and the cooperating magnet surface at a plurality of positions to thereby cause a greater number of flux linkages to exist between the armature and the face plate of the magnet assembly. This would then mean that there would be a stronger sealing force between the magnet and its cooperating armature and further that once the armature begins to leave the surface of the magnet, the air gap between the armature and the magnet is increased by the number of times that the magnetic flux enters and leaves the armature. Thus, the air gap will be rapidly increased and the magnetic attraction between the armature and magnet will rapidly decrease so as to allow extremely rapid movement of the armature to disengaged position.

As best seen in Figure 4, the magnetic plates 76, 78, 86, the core member and polarizing coil 84 are rigidly connected as a unit hereinafter to be called the polarizing magnet of the magnetic latch structure. This polarizing magnet has a pair of side plates 94 and 96 attached thereto as best seen in Figures 1, 2, 3 and 4, these side plates providing means for pivotally mounting the magnet assembly as seen in Figures 2 and 3 by shaft 98 which cooperates with apertures 100 and 102 of side plates 94 and 96 seen in Figures 1 and 4. Clearly, the pivotal mounting shaft 98 is supported from apertures in saddle support members 56 and 58, one such aperture being seen as aperture 104 in saddle support member 58 of Figure l.

The pivotal mounting shaft 98 further acts to pivotally support a walking beam 106 which is best seen in Figures 1 and 2. Walking beam 106 has the armature member 92 pivotally connected to one end thereof by means of the protruding ear 108 of armature 92 which has an aperture therein which passes a pivotal mounting pin 110 (Figure 2) through a cooperating aperture at the bottom of walking beam 106.

Accordingly, it is seen that the magnet assembly 72 of Figures 1 and 2 as well as the armature 92 which is fastened to walking beam 106 are pivotally, mounted on a common pivotal shaft which is supported from the saddie support members 56 and 58.

The upper end of walking beam 106 is pivotally mounted to one end of each of opening spring shaft 112 which carries a relatively powerful opening spring 138 and movable contact shaft 114 which is operatively connected to movable contact assembly 70.

The movable contact assembly 70 may be of any desired type well known in the art and in the case of the instant application is comprised of a first contact portion 116 having contact surfaces 118 and 120 and a back-up biasing member 122. Each of members 116 and 122 are pivotally mounted on a contact block 124 as seen in Figures 1 and 2 by means of a pivotal mounting pin 126 which is biased into a U-shaped receiving portion of contact block 124 by the biasing spring 128. The contact block 124 is then electrically and mechanically connected to the conductor 68 which in turn is electrically and mechanically connected to the lower terminal members 20 and 22.

The function of the back-up member 122 is to bring the biasing force of biasing springs such as spring 130 into play to resiliently force the contact surfaces 118 and 120 into contact engagement with the cooperating stationary contact surfaces of the stationary contact 132 of Figures 1, 1a, 5 and 6 when the movable contact is moved to the engaged position.

It is to be noted that walking beam 106 passes through an aperture 134 in V-shaped structural member 136. Structural member 136 bridges the saddle support members 6 and 58 and is connected to flanges 138 and 140 of the saddle support members 56 and 58 respectively, as seen in Figure 1. The opening spring shaft 112 passes through a cut-away portion 137 in the V-shaped support member 136as seen in Figures 1 and 2 and the portion of shaft 112 behind member 136 supports the opening spring member 138 which is contained between a collar 141 (Figure 3) and the back surface of structural n1emher 136.

Hence, when the walking beam 106 is rotated in a counterclockwise direction, the movable contact assembly will be rotated about pivot point 126 to a disengaged position and collar 141 of shaft 112 will be moved backwards to allow extension of compression spring 138. When, however, walking beam 106 is rotated in a clockwise direction, spring 138 will become charged because of the rightward motion of shaft 112 and collar 141 with respect to member 136, and the movable contact assembly 70 will be rotated in a clockwise direction and into an engaged position with respect to the stationary contact 132 of Figures 1 and 1a.

Accordingly, a first feature of my novel invention is seen to comprise the novel construction of the magnetic latch wherein the armature member and the polarizing magnet for the armature member are independently rotatable with respect to one another.

Thus, as will be seen hereinafter, when the contact mechanism is in its disengaged position and the armature members sealed thereto, an operating mechanism may be connected to the polarizing magnet to drive the polarizing magnet in a clockwise direction. This will then force the walking beam 106 to be rotated in a clockwise direction to thereby move the cooperating contacts to their engaged position against the biasing force of the opening spring 138. When, however, the magnetic flux between the polarizing coil and the armature is decreased and the force of spring 138 is sufiicient to pry the armature 92 away from the polarizing magnet, then the contact as- ,sembly 70 will be driven to its disengaged position by means of the force of biased spring 138 independently of 'the polarizing magnet and the operating means attached thereto. This action then imparts trip-free characteristics to the circuit breaker without requiring a relatively complex trip-free mechanism in the operating mechanism.

Hence, the operating mechanism may be of simple construction as that shown in Figures la, 8 and 9. More specifically, the operating mechanism of Figures 1a, 8 and 9 comprises a toggle assembly which includes adjustable link 142 which has a screw connection 144 connectible to shaft 146 supported by side plates 94 and 96 of the closing magnet as seen in Figures 1 and 2. This connection is best seen in Figure la which shows the complete assembly of the operating mechanism and magnetic latch mechanism.

Toggle link 142 is pivotally connected to a second toggle link 148 by pin 147 as seen in Figures 8 and 1a, the toggle link 148 being pivotally mounted on a shaft 150 as seen in Figures 8 and 9. The shaft 150 is then supported from support angle members 40 and 42 in the manner shown in Figure 9.

A first portion of toggle member 148 supports a pin 152 which is pivotally connected to one end of connecting link 154. The other end of link 154 is pivotally connected to solenoid plunger extension 156 by means of the pin 158 carried by the solenoid plunger extension 156.

The lower end of toggle member 148 is biased to rotate in a clockwise direction about shaft 150 by biasing spring 160 which is attached to structural member 162. The lower end of toggle link 148 is further positioned to move in cooperating relationship with respect to a roller 164 of the microswitch 166 which operates to deenergize the solenoid energizing circuit responsive to operation thereof as will be described hereinafter.

An adjustable stop member 168 is then positioned in cooperating relationship with respect to a flange 170 of link 148 as seen in Figure 8, this stop mechanism checking the motion of toggle links 142 and 148 once the solenoid plunger 156 positions them in the overcenterposition shown in Figures 8 and 1a.

The solenoid mechanism is connected to structural member 172 of Figures 8 and 9 and is best seen, in Figure 811 as comprising a magnetic plunger portion 174 which moves within an energizing coil (not shown) in a manner well known in the art.

A dash-pot action is imparted to plunger 174 by means of the piston member 176 connected to the right hand end of plunger 174 in Figure 8a. This piston member 176 moves within a cylinder 178 which is enclosed by an end member 180 having an air valve 182 therein which is adjusted by the screw means 184, the air valve 182 controlling the motion of plunger 174 under any given force.

Figure 8 further shows a link 186 having one end pivotally connected at pin 152 and its other end pivotally connected to link 188 by pin 190. Thus the link 188 may control auxiliary switches or an indicating mechanism positioned within indicating block 192 which gives a visual indication of the position of the circuit breaker operating mechanism.

Returning now to Figures 1, la, 5, 6 and 7, it is seen that the circuit breaker current path includes terminals 20 and 22 which are connected to the common conductive member 68, the movable contact structure 70, and the stationary contact structure 132. The stationary contact structure 132 is, as best seen in Figures 1 and 6, fastened to a conductive bar 194 by means of bolts. 196 and 198 and the conductive member 194- is mechanically supported from support posts 24 and 26 by the angles 200 and 202 best seen in Figure 1. Angles 200 and.202 are further seen in Figures 1, 5 and 7 as being carried by the support structures 24 and 26 by a bracket arrangement similar to that set forth above in Figure 3, for bracket arrangement 28.

One end of each of two-turn blow-out coils 204, 206, 208. and 210 which will be described in more detail hereinafter, is connected to conductive member 194 and the opposite end of blowout coils 204 and 206 are connected to upper terminal 46 while the upper end of blowout coils 208 and 210 are connected to upper terminal member 48.

Thus the complete current circuit from stationary contact 132 will include conductive bar 194, blow-out coils 204, 206, 208 and 210, and upper terminals 46 and 48.

As described hereinbefore, it is necessary that a magnetic flux be generated in the magnetic latch structure which is proportional to or functionally related to the current in the circuit breaker circuit. In the past, this has been done by taking a bucking bar which is a current conductor directly through the magnetic circuit, thus immobilizing the magnet portion of the magnetic circuit and increasing the length of the current path. In accordance with my invention, however, I provide a magnetic shunt 212 which is fastened to conducting member 68 by the bracket means 214 as seen in Figures 1, 2 and 3, the bracket member 214 being fastened to conducting member 68 by the bolt 216. As best seen in Figure 3, the magnetic shunt which is an open ring of magnetic material surrounds the stationary portion of the moving contact structure 70 and terminates on either side of the magnetic latch at the position of front plate 86 of Figure 4. Hence, a magnetic flux will be generated through the plate 86 of Figure 4 in accordance with the current magnitude flowing through the circuit breaker contacts.

This flux will normally aid the flux generated by polarizing coil 84 in maintaining armature 92 sealed to the surface of magnetic plate 86. When, however, this flux is reversed or altered in some predetermined manner, the flux holding the armature 92 in its sealed position will be decreased to thereby allow the armature to be pried away from its sealed position by the opening spring 138 as seen in Figures 1 and 2.

Thus it is seen that my novel magnetic latch is an extremely compact and easily manufactured device, and further allows the use of a relatively short current path for the circuit breaker components. Furthermore, the magnet is movable with respect to magnetic shunt 212 since it is positioned in an air gap of the shunt.

As previously set forth, my novel magnetic latch allows the use of highly desirable anti-bounce means, this being shown in Figures 1 and 2, as comprising the open latch members 218 and 220 which are pivotally mounted on shaft 222 which is supported by extending arms 224 and 226 which are rigidly connected to magnet plates 76 and 78 respectively.

It is further seen that the open latch plates 218 and 220 have downwardly sloped engaging surfaces 228 and 230 respectively which are positioned to be engageable with respect to pin 232 carried by shaft 112 of the opening spring mechanism. Furthermore, the open latch members 218 and 220 are biased in a counterclockwise direction by means of a biasing spring 234.

The operation of my high speed circuit breaker heretofore described may now be given in the following in conjunction with the schematic illustrations of Figures 10, a, 11 and 12.

Assuming that the circuit breaker is in the engaged position as shown in Figures la and 10, it is seen that the toggle links 144 and 148 of the operating mechanism have been driven to the over-center position shown so that the toggle link 148 lies against the stop member 168. This will maintain the polarizing magnet 72 in the position shown in Figure la and since the armature 92 is sealed to the polarizing magnet 72, the latch force of the toggle linkage is transmitted directly to the walking beam 106 and the movable contact assembly 79 whereby the movable contact assembly is maintained in an engaged position with respect to stationary contact 132 against the force of opening spring 138.

The current through the movable contact assembly 70 will generate a flux in the magnetic shunt 212 (see Figure 10a) which is impressed upon the polarizing magnet (seen in dotted lines in Figure 10a) so as to aid the flux of the polarizing coil 84 in keeping armature 92 sealed to the polarizing magnet. When, however, the current through the movable contact reverses and the flux in magnetic shunt 212 similarly reverses the sealing force between armature 92 and the polarizing magnet is weakened and the opening spring 138 will drive the walking beam 106 in a direction to pry the armature 92 away from its magnet and to drive the movable contact structure to a disengaged position as seen in Figure 11.

As the opening spring shaft 112 reaches the end of its motion, the pin 232 of Figures 1 and 2 will pick up the surfaces 228 and 230 of the open latch members 218 and 220 respectively to rotate them in a clockwise direction about their pivotal mounting shaft 222 and against the biasing force of biasing spring 234.

As the shaft 112 continues to move, the pin 232 will reach the notches 236 and 238 in members 218 and 220 respectively, whereby the biasing force of spring 234 will quickly rotate the members 218 and 220 in a counterclockwise direction to firmly seat pin 232 in notches 236 and 238 as seen in the dotted lines in Figure 2.

It is to be noted that magnet structure 72 will still be in the position shown in Figures 1 and 1a and 11 since the speed of resetting magnet 72 is extremely slow when compared to the speed of operation of the movable contact assembly under the driving force of spring 138.

Hence, when the shaft 112 of Figures 1 and 2 reaches the end of its stroke, it will be firmly engaged by the anti-bounce mechanism including members 218 and 220 and it will not be possible for the movable contact assembly to rebound towards an engaged position because of the mechanical interlock between pin 232 and notches .236 and 238.

After the contact assembly has been moved to its disengaged position and the anti-rebound mechanism has firmly locked the movable contact assembly against rebound, the magnet assembly 72 will be slowly rotated about its pivotal mounting shaft 98 under the biasing force of reset spring (Figures 8 and 1a) which is attached to the lower end of toggle link 148 toward the reset position of Figure 12. As this magnet assembly 72 is slowly reset, it is seen that notches 236 and 238 will be moved out of engagement with pin 232 of contact shaft 112, the contact mechanism being maintained in the disengaged position by virtue of biasing action of spring 138 against plate 136.

The rate at which spring 160 will move the magnet assembly 72 to a reset position is given by the adjustment of valve 182 of the dash-pot solenoid mechanism of Figure 8a. Thus the magnet assembly can be made to reset as slowly as desired in order to allow the antirebound mechanism to latch the contact link 112 against rebound after the initial opening interval and prior to the engagement of the anti-rebound mechanism, and also to allow a slow engagement between the cooperating surfaces of armature 92 and face plate 86 of polarizing magnet 72.

The polarizing magnet 72 will finally reach the reset position of Figure 12 and the polarizing flux of coil 84 will once again cause the armature member 92 to be sealed against the polarizing magnet structure.

In order to reclose the circuit breaker, it is only necessary to apply a closing force to the toggle linkage of Figure 12 as indicated by arrow F. In the particular embodiment set forth herein, the solenoid means of Figure 8a is energized through any desired energizing circuit (not shown), whereupon the solenoid plunger 174 will be driven to the left in Figure l and the plunger 156 which is connected to link 148 by pin 152 will cause the toggle mechanism to be driven towards the position shown in Figures 8 and 10. The polarizing magnet and armature which are magnetically sealed to one another will drive the contact assembly to its engaged position.

Once the toggle mechanism including toggle links 142 and 148 assume their over-center position of Figure 10, the lower end of toggle link 148 will engage roller 164 of micro-switch 166 of Figure 8 to cause deenergization of the solenoid energizing circuit and the circuit breaker will be maintained in its engaged position in view of the latching action of the over-center toggle. If, however, the circuit breaker is engaged against a fault condition, the armature 92 will be released from its cooperating magnet because of the flux change in magnetic shunt 212 and the circuit breaker contacts will be disengaged independently of the operating mechanism position.

Hence by the use of my novel magnetic latch unit, I can achieve trip-free characteristics independently of the operating mechanism construction.

As described above, the further feature of this novel invention is that the blowout coils are positioned on either side of the contact structure so as to offer a greater cooling area to the cooling medium, such as the air in which the coils are immersed. By increasing this cooling area, it is clear that the cross-sectional area of conductors used in the blow-out coils may be decreased.

This novel feature is specifically set forth in Figures 1, 5 and 6, which show the blow-out coils heretofore described as blow-out coils 204, 266, 208 and 210.

It will be noticed that coils 294 through 218 aretwoturn coils which are connected in series with terminals 46-48 and the common stationary contact bar 194. Each of the coils are connected in parallel with one .another and wound so as to induce a flux in the same direction through the contact area at which arcing will occur when the movable contact 70 is moved to a disengaged position with respect to the stationary contact 132.

It is to be noted that an arc chute means of the type set forth in United States Patent No. 2,381,637, issued August 7, 1945, entitled Arc Quencher, to D. I. Bohn, will be utilized in conjunction with this blow-out means, but has not been shown herein to simplify the drawings.

It is essential to note that in this novel blow-out coil construction, the coils 204 and 206 are on one side of the contacting area, while coils 298 and Zltl are on the opposite side of the contacting area.

That is to say, this invention separates cooperating parts of the blow-out coil into more than one location in order to expose a greater surface area for cooling purposes while still maintaining the same flux densities across the contact area as would be present if the coil were a continuous member.

Although I have here described preferred embodiments of my novel invention, many variations and modifications will now be evident to those skilled in the art and I prefer, therefore, to be limited, not by the specific disclosure herein, but only by the appended claims.

I claim:

1. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged posi"on and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another.

2. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively con nectedvto said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; said first portion of said magnetic latch being positioned in a reset position when said relatively movable contact is in said disengaged position, said second portion of said magnetic latch being movable to a cooperating reset position with respect to said first portion to be sealed to said second portion, said operating means thereafter being operatively connected to said relatively movable contact to move said relatively movable contact to said engaged position through said magnetic latch.

3. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of saidmagnetic latch means being magnetically scalable with respect to one another; said first portion of said magnetic latch being positioned in a reset position when said relatively movable contact is in said disengaged position, said. second portion of said magnetic latch being movable to a cooperating reset position with respect to said first portion to be sealed to said second portion, said operating means thereafter being operatively connected to said relatively movable contact to move said relatively, movable contact to said engaged position through said magnetic latch; and latch means associated with said operating means to maintain said relatively movable contact in said engaged position.

4. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; the magnetic seal between said first and second portions of said magnetic latch being defeated responsive to a predetermined current change in current flow through said relatively stationary and relatively movable contacts when said relatively movable contact is in said engaged position.

5. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; said first portion of said magnetic latch being positioned in a reset position when said relatively movable contact is in said disengaged position, said second portion of said magnetic latch being movable to a cooperating reset position with respect to said first portion to be sealed to said second portion, said operating means thereafter being operatively connected to said relatively movable contact to move said relatively movable contact to said engaged position through said magnetic latch; and latch means associated'with saidopcrating means to maintain said relatively movable contact in said engaged position; the magnetic seal between said first and second portions of said magnetic latch beingdetested responsive to a predetermined current change in current flow through said relatively stationary and relatively movable contacts when said relatively movable contact is in said engaged position.

6. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of saidmagnetic latch comprising a first source of polarizing flux. I

7. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operative ly connected to said operating means; said first and second portions of said magnetic latch means being magnetically sealable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing fiux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner.

8. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to saidioperating means; said first and second portions of said magnetic latch means being magnetically sealablewith respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; said magnetic latch forming a tripfree connection between said relatively movable contact and said operating means.

9. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; open ating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; said first portion of said magnetic latch being positioned in a reset position when said relatively movable contact is in said disengaged position, said second portion of said magnetic latch being movable to a cooperating reset position with respect to said first portion to be sealed to said second portion, said operating means thereafter being operatively connected to said relatively movable contact to move said relatively movable contact to said engaged position through said magnetic latch; and latch means associated with said operating means to maintain said relatively movable contact in said engaged position; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux being generated through a stationary magnetic path and responsive to current conditions through said circuit breaker; said second source of flux and said stationary magnetic path being constructed to decrease the net flux sealing said first and second mag- .netic latch portions when said current conditions through said circuit breaker change in a predetermined manner; said magnetic latch forming a trip-free connection between said relatively movable contact and said operating means.

10. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net fiuX sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; said second source of flux being relatively stationarily mounted with respect to said first and second portions of said magnetic latch, at least one of said first or second portions of said magnetic latch being movable into registry with said second source of flux when said relatively movable contact is moved to said engaged position.

11. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said rel-atively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing meansand a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; said second source of flux being relatively stationarily mounted with respect to said first and second portions of said magnetic latch, at least one of said first or second portions of said magnetic latch being movable into registry with said second source of flux when said relatively movable contact is moved to said engaged position; said second source of flux comprising a magnetic shunt surrounding a current conductor of said circuit breaker and having said one of. said portions movable into an air gap in said shunt responsive to moving said movable contact to said engaged position.

12. A high speed circuit breaker comprising arelatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically sealable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net fiux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; and biasing means operatively connected to said magnetic latch and said operating means for resetting said magnetic latch toward said reset position when said magnetic seal between said first and second portions is broken.

13. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contactmovable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing'said relatively movable contact towards said disengaged posi tion; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; said biasing means having time delay means associated therewith to slow down the motion of said second magnetic portion when said second magnetic portion of said latch is moved toward said reset position.

14. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically scalable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; said second source of flux being relatively stationarily mounted with respect to said first and second portions of said magnetic latch, at least one of said first or second portions of said magnetic latch being movable into registry with said second source of flux when said relatively movable contact is moved to said engaged position; said second source of flux comprising a magnetic shunt surrounding a current conductor of said circuit breaker and having said one of said portions movable into an air gap in said shunt responsive to moving said movable contact to said engaged position; and biasing means operatively connected to said second portion of said magnetic latch and said operating means for resetting said magnetic latch toward said reset position when said magnetic seal between said first and second portions is broken; said biasing means having time delay means associated therewith to slowdown the motion of said second magnetic portion when said second magnetic portion of said latch is moved toward said reset position.

15. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latchmeans comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions' of said magnetic latch means being magnetically scalable with respect to one another; said first portionof said magnetic latch" being positioned in a reset position when said relatively movable contact is in said disengaged position, said second portion of said magnetic latch being movable to a cooperating reset position with respect to said first portion to be sealed to said second portion, said operating means thereafter being operatively connected to said relatively movable contact to move said relatively movable contact to said engaged position through said magnetic latch; and anti-rebound means comprising a first rebound latch means carried by said second magnetic latch portion and a second anti-rebound means operatively connected to said relatively movable contact; said first and second anti-rebound means being latchably engageable with re spect to one another; said first anti-rebound latch means latchably engaging said second anti-rebound means when said relatively movable contact is moved to said disengaged position; said latchable engagement being defeated when said second magnetic latch portion is moved to said reset position.

16. A high speed circuit breaker comprising a relatively stationary contact and arelatively movable contact movable between an engaged position and la disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means -to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically sealable with respect to one another; said first portion of said magnetic latch being positioned in a reset position when said relatively movable contact is in said disengaged position, said second portion of said magnetic latch being movable to a cooperating reset position with respect to said first portion to be sealed to said second portion, said operating means thereafter being operatively connected to said relatively movable contact to move said relatively movable contact to said engaged position through said magnetic latch; and latch means associated with said operating means to maintain said relatively movable contact in said engaged position; the magnetic seal between said first and second portions of said magnetic latch being defeated responsive to a predetermined current change in current flow through said relatively stationary and relatively movable contacts when said relatively movable contact is in said engaged position; and anti-rebound means comprising a first rebound latch means carried by said second magnetic latch portion and a second anti-rebound means operatively connected to said relatively movable contact; said first and second anti-rebound means being latchably engageable with respect to one another; said first anti-rebound latch means latchably engaging said second anti-rebound means when said relatively movable contact is moved to said disengaged position; said latchable engagement being defeated when said second magnetic latch portion is moved to said reset position.

17. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively station contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable conto said operating means; said first and second portions of said magnetic latch means being magnetically sealable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; and anti-rebound means comprising a first rebound latch means carried by said second magnetic latch portion and a second anti-rebound means operatively connected to said relatively movable contact; said first and second antirebound means being latchably engageable with respect to one another; said first anti-rebound latch means latchably engaging said second anti-rebound means when said relatively movable contact is moved to said disengaged position; said latchable engagement being defeated when said second magnetic latch portion is moved to said reset position.

18. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said relatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magnetically sealable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said circuit breaker change in a predetermined manner; and biasing means operatively connected to said magnetic latch and said operating means for resetting said magnetic latch toward said reset position when said magnetic seal between said first and second portions is broken; and anti-rebound means comprising a first rebound latch means carried by said second magnetic latch portion and a second anti-rebound means operatively connected to said relatively movable contact; said first and second anti-rebound means being latchably engageable with respect to one another; said first antirebound latch means latchably engaging said second antirebound means when said relatively movable contact is moved to said disengaged position; said latchable engagement being defeated when said second magnetic latch portion is moved to said reset position.

19. A high speed circuit breaker comprising a relatively stationary contact and a relatively movable contact movable between an engaged position and a disengaged position with respect to said relatively stationary contact; an opening biasing means operatively connected to said elatively movable contact for biasing said relatively movable contact towards said disengaged position; operating means for moving said relatively movable contact toward said engaged position against the force of said biasing means and a magnetic latch means for operatively connecting said operating means to said relatively movable contact; said magnetic latch means comprising a first 19 movable portion operatively connected to said relatively movable contact and a second movable portion operatively connected to said operating means; said first and second portions of said magnetic latch means being magneticallysealable with respect to one another; and means for generating a magnetic flux for magnetically sealing said first and second portions of said magnetic latch comprising a first source of polarizing flux; and a second source of flux responsive to current conditions through said circuit breaker; said second source of flux being constructed to decrease the net flux sealing said first and second magnetic latch portions when said current conditions through said current breaker change in a predetermined manner; said biasing means having time delay means associated therewith to slow down the motion of said second magnetic portion when said second magnetic portionof said latch is moved toward said reset position; and anti-rebound means comprising a first rebound latch means carried by said second magnetic latch portion and a second anti-rebound means operatively connected to said relatively movable contact; said first and second antirebound means being latchably engageable with respect toone another; said first anti-rebound latch means latch ture; said armature comprising at least one relatively non,

magnetic portion positioned to cause the said magnetic flux linking said magnetic body and said armature to to enter and leave said armature a first and second time.

References Cited in the file of this patent UNITED STATES PATENTS Bohn Aug, 7, 1945 2,555,799 Lerstrup -e JuneS, 1951 2,687,462 Cellerini Aug. 24, 1954 

